1. Field of the Invention
The present invention is directed to a system for direct injection of chemicals or other additives in a liquid solution into a spray nozzle. The injection system of the present invention may be mounted adjacent, or in close proximity, to the spray nozzles of a sprayer. The present invention comprises a variable speed/stroke diaphragm pump capable of providing a double pumping action such that a liquid solution may be continuously pumped at a controllable rate to one or more spray nozzles of a sprayer.
2. Description of the Prior Art
Traditional agricultural spray systems require the mixing of agrochemical formulation with a water carrier in a sprayer tank. Traditional sprayers pump the mixture of chemical and water to the boom and out through spray nozzles. Errors in chemical measurement, mixing, and calibration, result in increasingly burdensome problems regarding to the disposal of leftover tank mixes, which are frequently considered to be hazardous wastes. Additionally stringent worker protection standards regarding potential exposure to chemicals and accountability standards for disposal of chemicals provide drawbacks which discourage the use of traditional sprayers.
Another approach to agrochemical spraying is direct chemical injection. Direct chemical injection provides benefits of reduced worker exposure, accurate chemical dispensing, reduced waste disposal, and adaptability to variable rate applications. Presently available direct injection systems inject the chemical near the pump or into a spray line that is not located in close proximity to the spray nozzle. A time delay, results between the point of injection and the point of nozzle output. This delay is a problem when trying to match variable chemical rates with particular locations in an agricultural field from a moving sprayer. It is customary for agrochemical boom sprayers to move at velocities from 4-18 mph.
Another problem associated with prior art direct injection systems is their inability to accurately meter the low flow rates associated with agrochemical spraying. Typical application rates for new agrochemical chemistries are as low as 2 ounces per acre. The use of orifices to restrict flow rates for agrochemical mixtures is limited because orifices of diameters less than 0.03 inches inheritantly plug up with formulation debris. Additionally, the regulation of pressures below 10 psi is difficult due to regulator drift. Thus, traditional means of using pressure regulation across orifices to control flow rate have been less than satisfactory with the low flow rate requirements for agrochemical applications.
The present invention provides an apparatus capable of injecting chemicals or other additives in a liquid solution into a spray nozzle at a controllable variable rate for flow rates as low as 1 ml/min. This flow rate corresponds to an application rate of approximately 2 ounces per acre for a boom sprayer moving at 5 mph and comprising a 20 inch nozzle spacing. The design of the present invention permits the injection pump to be placed very close to the outlet spray device or spray nozzle, thereby avoiding time delay problems associated with prior art devices. This invention has many varied applications, including but not limited to, agricultural spraying, food processing and liquid fuel delivery.